Linux--Centos7 processes and scheduled tasks

I. 1. Understand the relationship between programs and processes

2. View process information PS View static processes at the current time

ps command is the most commonly used process viewing tool in Linux operating system, mainly used to display the process including the currently running

A static snapshot of complete information about each process. Process information can be selectively viewed through different command options.

a: Displays all process information under the current terminal, including processes of other users. When combined with the "x" option

Displays information about all processes in the system.

u: Output process information in a user-oriented format.

x: Displays the progress information of the current user under all terminals.

**1. Understand the meaning of process information

USER: The name of the user account that started the process.

PID: The numeric ID number of the process in the system, unique to the current system.

%CPU: Percentage of CPU used.

%MEM: Percentage of memory used.

VSZ: Size of virtual memory (swap space) occupied.

RSS: Size of resident memory (physical memory) occupied.

TTY: Indicates on which terminal the process runs. "? "indicates that the terminal is unknown or not required.

STAT: Displays the current status of the process, such as S (dormant), R (running), Z (dead),